Method for monitoring the energy density of a laser beam by image analysis and corresponding device

Abstract

A method for monitoring the energy density of a laser beam using parameters of the laser beam including regularly applying the laser beam to a reference substrate and measuring, with each application, the resulting light intensity; identifying a change in the light intensity on the reference substrate between at least two measurements; and, when the change in the light intensity is higher than a predetermined threshold, determining the unstable parameter or parameters of the energy density of the laser beam.

Description

FIELD OF THE INVENTION[0001]The invention relates to the field of manufacturing parts by Selective Laser Melting (SLM), i.e. a technique for additive manufacturing capable of producing metal parts by means of high power lasers gradually and locally melting, i.e. in a selective way, a metal powder in a controlled atmosphere.TECHNOLOGICAL BACKGROUND[0002]Selective laser melting is a method allowing the manufacturing of a molded body, for example a prototype of a product or of a component, according to three dimensional CAD data of a model of a molded part by deposition of layers of a material as a powder. Several layers of the powder are successively deposited on each other, so that each powder layer is heated to a temperature determined by a focused laser beam of high power (from 200 W to a few kW) applied on a given area of the powder layer corresponding to a determined cross-section area of the model of the molded body, before depositing the next layer. The laser beam is guided abo...

AI Technical Summary

Benefits of technology

The invention proposes a method for controlling the energy density of a laser beam that is cost-effective and can be industrialized for use in the manufacturing space. The method allows for quick detection of changes in the power, velocity, and size of the laser beam, addressing the drawbacks of current methods that are more expensive and limited in use.

Problems solved by technology

Nevertheless, this monitoring has the drawback of requiring individual measurements which are successively carried out by different apparatuses.

In addition to being long and difficult to apply in industry, this monitoring of the energy density of the laser beam is not robust, the measurements undergoing the risk of being distorted by drifts of the apparatuses used.

These apparatuses are further specific and often require training and particular skills in order to be used, are further expensive, fragile and long to apply and have to be periodically checked.

Finally, the whole of the manufacturing space is not accessible for allowing these measurements.

However, this method by no means allows determination of whether the energy density of the laser beam is stable, or whether one of the parameters on which it depends is unstable.

None of these documents therefore proposes a reliable and fast means for detecting a drift of the parameters of the energy density in a simple way and for moderate cost.

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